Direct fuel injection circuits in internal combustion engines comprise a pilot-operated valve which can be directly connected to a common rail distributing fuel under pressure to injectors. The valve is normally closed and can be actuated to open a passage and allow fuel to leave thus permitting continuous control of the pressure in the injection circuit.
Valves are known inter alia comprising a tubular body in which a needle piloted by an electromagnetic actuator obturates or opens the outlet passage of the fuel. In normal operation the passage is closed and its closure is ensured by the piloted actuator which applies to the needle a closure force opposing the opening force applied to the needle by the pressurised fuel. A valve is known from EP1915557 comprising a magnetic body on which are stacked the shell of the coil of the electromagnet, a sealing gasket and the coil itself. The assembly is held in place by a wedging washer. However this arrangement is not liquid-tight as a fluid foreign to the carburettor, water for example, can enter the shell by passing around the washer.
It has become urgent to propose completely liquid-tight valves which are easy to manufacture and assemble.